configure.ac:
AC_CHECK_FUNCS_ONCE([strdup])
-gl_LIBUNISTRING_LIBSOURCE([0.9], [unistr/u8-strdup.c])
+gl_LIBUNISTRING_MODULE([0.9], [unistr/u8-strdup])
Makefile.am:
+if LIBUNISTRING_COMPILE_UNISTR_U8_STRDUP
+lib_SOURCES += unistr/u8-strdup.c
+endif
Include:
"unistr.h"